The reason this is surprising is that the highly anticipated Lumia 920T started shipping to China Mobile in January. China Mobile has subsidized the price of the 920T strongly and the model sold out repeatedly during February as new shipments arrived to major cities like Shanghai and Beijing. There have been plenty of reports about the strong marketing support China Mobile is giving the 920T, the most important Windows phone of the winter. Nobody expected the 920T to give a massive boost to Windows in the first quarter of 2013, but an outright market share decline would be a nasty surprise.

How is it possible that Windows Phone’s market share is moving down in China during the quarter when the most high-profile Windows model in a year arrived backed by a carrier with 730 million subscribers? The nightmare scenario here is that Windows is stuck with mid-single digits market share in major markets like the United States and China, no matter what happens on the product front. There is a small core group of Windows fans who rush into shops to buy a hot new device, but that group is not expanding. That would explain why there can be sell-outs of certain flagship models like the Lumia 920 at AT&T in December or the Lumia 920T at China Mobile in February without any real impact on the market share landscape.